basic touch test using gtk and touch events

touchy.py

#!/usr/bin/env python

import cairo
from gi.repository import Gdk
from gi.repository import Gtk

colors = ['a40000', '75507b', '8ae234', '729fcf', 'f57900',
          'c4a000', 'ce5c00', 'eeeeec', '4e9a06', '204a87']

def next_idx(seq):
    values = seq.values()
    for i in xrange(0, 10):
        if i not in values:
            return i
    return 0

def on_touch_event(drawing_area, event, seq):
    surface = drawing_area.surface
    if surface:
        if event.touch.type == Gdk.EventType.TOUCH_BEGIN:
            seq[event.touch.sequence] = next_idx(seq)
        cr = cairo.Context(surface)
        cr.rectangle(event.touch.x - 5, event.touch.y - 5, 10, 10)
        i = seq[event.touch.sequence]
        c = colors[i]
        t = int(c[0:2],16)/255.0, int(c[2:4],16)/255.0, int(c[4:6],16)/255.0
        cr.set_source_rgb(*t)
        cr.fill()
        drawing_area.queue_draw()
        if event.touch.type == Gdk.EventType.TOUCH_END:
            del seq[event.touch.sequence]

def on_draw(drawing_area, cr):
    if not drawing_area.surface:
        return
    alloc = drawing_area.get_allocation()
    cr.set_source_surface(drawing_area.surface, 0, 0)
    cr.rectangle(0, 0, alloc.width, alloc.height)
    cr.paint()

def on_size_allocate(drawing_area, alloc):
    if hasattr(drawing_area, 'surface'):
        del drawing_area.surface
    drawing_area.surface = None
    window = drawing_area.get_window()
    if window:
        drawing_area.surface = window.create_similar_surface(0x1000, alloc.width, alloc.height)

if __name__ == '__main__':
    sequences = {}
    w = Gtk.Window()
    w.connect('delete-event', lambda *_: Gtk.main_quit())
    a = Gtk.DrawingArea(visible=True)
    a.connect('draw', on_draw)
    a.connect('touch-event', on_touch_event, sequences)
    a.connect('size-allocate', on_size_allocate)
    a.add_events(Gdk.EventMask.TOUCH_MASK)
    w.add(a)
    w.present()
    Gtk.main()